The folks at Mettatec.com just released a DIY Kit to turn the M2 into a GNSS Base Station. Even though it’s still in backorder it looks interesting. What I see is that they use a multiband antenna with up to 44dB of gain:
B2 / L2 / G2 / B3 / E5b / E6: 44dB
B1 / L1 / G1 / E1 / E2: 42dB
And I see an image that shows a very interesting centimeter precision in single mode.
Has anyone already tried it?